This invention is directed to pick-up heads of the type disclosed in commonly assigned U.S. Pat. Nos. 3,512,206 and 3,545,181 in the name of Bernard W. Young issued respectively on May 19, 1970 and Dec. 8, 1970 and respectively titled AIR FLOW SURFACE CLEANING APPARATUS and AIR CLEANING APPARATUS.
The latter patents disclose a vehicle which carries a pick-up head, a centrifugal separator, a hopper, and assignee's REGENERATIVE.RTM. air circulating system. Air generated by a turbine is directed through a blast orifice of the pick-up head, admixes with and propels the debris to a suction orifice of the pick-up head after which the debris is centrifugally separated and discharged in the hopper, and the air returns to the blast orifice. In this manner debris on roads, roadways, tarmacs, parking lots or the like can be rapidly and efficiently removed. However, while the apparatus of the latter patents represented the state-of-the-art at the time of patenting and continues to do so to date, continued experimentation, research and development has resulted in yet greater efficiency and higher speeds of both debris removal and vehicle travel. Furthermore, the art of road sweepers has advanced considerably since the early 1970's and has become considerably more sophisticated and specialized. Most recently U.S. Pat. No. 4,773,121 was granted on Sep. 27, 1988 to the common assignee, and discloses an improved pick-up head of aerodynamic shape having minimum pick-up head to ground clearance so as to maximize blast air velocity. The latter assures that debris, particular small high mass debris, such as grains of sand, pebbles, pea-gravel or the like can be cleaned from surfaces, specifically and particularly airport runways, tarmacs and the like.